Crozet's Blue Ridge Tunnel

Smoke-removal: He built a Burgoyne exhaust system, in which inverted tubs trapped the fumes and, after they were immersed in water, expelled them into a network of pipes and valves.

Water-removal: He connected hand- and horse-powered pumps to an 1,800-foot length of three-inch iron pipe which discharged 60 gallons a minute and is believed to be the longest siphon on record.

Accuracy: Christmas Day, 1856, was bore-through day, when the holes from each side met. Crozet's calculations were so precise that only a half inch separated the alignment.

Cost: $488,000 or about $114 per foot

Ownership: The tunnel was originally part of the 17-mile Blue Ridge Railroad, an entity created by the Commonwealth of Virginia to handle the expensive task of breaching the Blue Ridge and opening up the Shenandoah Valley. It was part of the Virginia Central Railroad– purchased in 1869 by the C&O (now CSX).

Civil war role: The line brought food from the Shenandoah and Ohio Valleys to Richmond and on to Virginia's ports, and it carried troops and supplies back and forth as military campaigns surrounded its tracks. A prime target for Federal armies, this key Confederate line was constantly attacked, and by the end of the war had only about five miles of track still in operation and just $40 in the bank.

Retired: In 1944 after the C&O built a nearby newer and wider railroad tunnel.

Future: hiking, biking, horseback-riding

sources: American Society of Civil Engineers and the Chesapeake & Ohio Historical Society